Comment: Don't forget the dangers of overheating
Overheating is too often forgotten in the quest for energy efficiency but its significant impact means designers and planners need to integrate it into their thinking now, says Professor George Martin of Coventry University
It's only when we have a heatwave in this country that the idea of 'overheated homes' stops sounding like a joke.
A likely future of high energy prices combined with tough carbon reduction targets has made energy efficiency a priority for government, landlords and householders. Consequently, there has been a natural rush for insulation, lagging, sealing up homes. What else would we do, given the reputation of the British weather?
The summer weather has shown how rushing to improve energy ratings in homes has been done with the blinkers on. This short-sighted and inflexible thinking needs to change. Over time, overheating in homes will lead to increased deaths among vulnerable people (typically older people who live by themselves). We've already seen what can happen: 30,000 deaths attributed to the heatwave in western and central Europe during 2003 (around 2,000 of which were in the UK), along with an estimated economic loss of £7.5bn. At that time the UK's Climate Impact Programme (UK CIP) estimated that average 2003 summer temperatures in the UK – which peaked at 38.5ºC – would be close to the average summer temperature by 2045.
This summer’s hot spell may be seen as unusual, but with rising temperatures predicted and more extreme weather expected as a result of climate change, dealing with overheated homes will be a more common and major problem. Cooling homes is itself a problem, as more people will inevitably opt for air conditioning - which requires significantly more energy than heating, and reverses any efforts to make our homes less energy dependent. There is also a social issue - common to other parts of the world – where divides grow between householders who can afford the luxury of air conditioning and those who have to deal with uncomfortable, if not dangerous, homes.
We certainly don't need kneejerk reactions, a rush to air conditioning as standard. What's needed is a greater understanding of what it means for our houses to be 'resilient', flexible and adaptable enough to cope with the full range of future climate conditions, together with the associated energy costs and even energy availability that we are going to face for the future.
Planning and design
Overheating needs to be addressed at the planning and design stage. Plonking five or six 'standard' house types on an estate without considering orientation - their position in relation to sunlight - will simply not work for the future. The primary criterion for addressing future overheating is to limit both solar gain and internal gain and design achievable levels of venting. A secondary criterion is the provision of thermal mass, but it should be appreciated that this is less appropriate in domestic than non-domestic buildings due to their occupancy patterns.
At a time when government initiatives are battling to get householders to pay for the more obvious improvements to help with energy efficiency, it's a mixed message to begin talking about keeping cool in hot weather and what this means for property. No-one wants to derail progress on energy efficiency - which means more of a role for planners, designers, architects and housebuilders to ensure the responsibility for decision-making for the future is not all left with individual householders. The retrofitting challenge is already large and complex enough without storing up a further stage of problems for the future.
George Martin is professor of low impact and sustainable buildings at Coventry University, and is also an affiliate of Forum for the Future.